Re: [libmicrohttpd] Trying to understand libmicrohttpd versioning

[Tomas Heran]

On 02/13/2017 05:09 PM, Christian Grothoff wrote:
> Hi!
>
> I think what you're spotting is that I made a mistake in updating the
> library revision in the past, and failed to reset CURRENT (or bump AGE).
>
> We are at least 99.9%-compatible with .so.10 / 0.9.37, but there _may_
> have been some minor reason to bump the .so-level, not entirely sure
> which of the two mistakes I made in retrospect.

Hi Christian,

thanks you for the quick response. My testing did show that it is
backwards-compatible for my usecase, but I'm using just a small subset
of the microhttpd.h interfaces, so I wanted to double check before
working around the filename change on my end (I'm planning to deliver
a libmicrohttpd.so.10 -> libmicrohttpd.so.12 symlink ... at least
temporarily).

> Regardless, the only sane way forward at this point is to continue to
> stick to the libtool rules, as one cannot sanely go back to .10-levels,
> or to .12.0.  Naturally, when we go to .13, we should definitively make
> sure to reset CURRENT properly.

Not that it's "this case", just making sure I understand, but when
there's an incompatible change in the library, libtool documentation
says one should bump CURRENT up and reset AGE to 0.

E.g. if that would happen in 0.9.53, then things would be as follows:

LIB_VERSION_CURRENT=53
LIB_VERSION_REVISION=0
LIB_VERSION_AGE=0

resulting in libmicrohttpd.so.53.0.0.

Do I understand that correctly?

Thanks,
Tomas

> Happy hacking!
>
> Christian
>
> On 02/13/2017 04:55 PM, Tomas Heran wrote:
> > Hi,
> >
> > I'm trying to understand versioning of the libmicrohttpd library, esp.
> > when it comes to LIB_VERSION_* variables in configure and the resulting
> > -version-info in libtool.
> >
> > In our internal repository I'm upgrading from 0.9.37 to 0.9.52, i.e.:
> > (0.9.37) libmicrohttpd.so.10 -> libmicrohttpd.so.10.27.0
> > (0.9.52) libmicrohttpd.so.12 -> libmicrohttpd.so.12.40.0
> >
> > I see that in public releases 0.9.45 and 0.9.46 the LIB_VERSION_AGE has
> > not been bumped (stayed the same at 34). That is puzzling as the libtool
> > versioning part of the documentation doesn't seem to be mentioning the
> > case when one would bump CURRENT, but leave AGE as is.
> >
> > This effectively forces programs to be at least relinked (if not
> > rebuilt), because the libmicrohttpd.so.10 -> libmicrohttpd.so.10.27.0
> > no longer exists and is replaces by libmicrohttpd.so.12 ->
> > libmicrohttpd.so.12.40.0.
> >
> > Now, I do see some "interfaces" removed, e.g. MHD_connection_close()
> > renamed to MHD_connection_close_(), but as far as I understand, that
> > function is not a public interface and so as far as the programs using
> > this library are concerned, the new version of the library should still
> > be backwards-compatible, i.e. programs linked with the older library
> > should still work fine without rebuilding and relinking.
> >
> > What do I miss?
> >
> > Thanks,
> > Tomas

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